Abstract
A bridge structure is subjected to different external loads and environmental effects during its operation, which results in different types and degrees of damage to the structure during its service life. Reinforcement is often required to maintain regular operation and extend its service life. However, a reinforced bridge structure continues to be subjected to vehicle loads and environmental erosion. Therefore, research on the durability deterioration mechanisms and fatigue life decay of reinforced structures is key to ensuring the long service lives of bridge structures. To study the influence of freeze–thaw cycle erosion on the basic mechanical properties and fatigue characteristics of a bridge structure and a strengthened structure, 2 m long prestressed hollow slab beams were designed and fabricated based on the principle of a similarity ratio and subsequently pre-cracked by fatigue failure. The prestressed hollow slab beams were strengthened after fatigue damage by two methods: pasting steel plates and pasting carbon fiber cloths. After this, a freeze–thaw cycle test was conducted to study the dynamic and static mechanical index changes and the attenuation of the fatigue characteristics of the prestressed strengthened hollow slab beams under freeze–thaw cycle erosion. Meanwhile, a numerical model for reinforced structures was established based on the ABAQUS software to study the mechanisms governing the attenuation of the fatigue life of the prestressed hollow slab beams with different freeze–thaw cycles. The results showed that the deflections and strains observed for the two methods were less than those prior to reinforcement. For instance, the deflection in the span decreased by 14–15%, and the compressive strain decreased by 5.2% to 6%. Under the fatigue load, the prestressed hollow slab beams strengthened by the two methods could withstand a fatigue load cycle of 2 million, and the reinforced components exhibited good fatigue resistance. Under cyclic erosion and fatigue loading, the deflections and strains in the reinforced prestressed hollow slab beams were increased by varying degrees, such as a 30–40% increase in the tensile strain and a 65–70% increase in the span. The fatigue life of the reinforced hollow slab beams decreased with the increasing number of freeze–thaw cycles, and the decay rate of the fatigue life was accelerated.
Highlights
Under the action of adverse environmental erosion and vehicle reciprocating loads, bridges undergo different types and degrees of structural damage
The construction process of the prestressed hollow slab beam strengthened by pasting steel plates was as follows: 1 Surface grinding: the surface of the test plate was ground with a grinding wheel, the dust on the surface of the test plate was washed with clean water, and the surface was wiped with absorbent cotton dipped in acetone after the surface of the test plate was dry
Along with durability specifications [39], 50 freeze–thaw cycle erosion tests were conducted on test plates and corresponding test blocks reinforced by bonded steel plates
Summary
Under the action of adverse environmental erosion and vehicle reciprocating loads, bridges undergo different types and degrees of structural damage. Yu [28] analyzed the effects of different stress levels on the fatigue properties of the reinforced concrete beams strengthened using carbon fiber cloth under freeze–thaw cyclic erosion. Based on experimental data, a numerical model for strengthened components was established, and the mechanisms of durability deterioration along with the law for the fatigue life decay of fatigue damaged prestressed concrete hollow slabs under the action of freeze–thaw cycle erosion were studied. The results of this study are of great significance for revealing the fatigue characteristics of prestressed hollow slab beams that have undergone corrosion by freeze–thaw cycles, as well as for understanding the durability degradation mechanism of actual bridge structure reinforcements, optimizing the reinforcement scheme, detecting and evaluating a reinforced bridge, and predicting the remaining life of a reinforced bridge structure
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